Resin composition, laminate, coverlay film, adhesive sheet, resin-coated metal foil, metal-clad laminate, printed circuit board, semiconductor device, and method for manufacturing resin composition

Abstract

The present invention provides a resin composition that stably exhibits a sufficiently high relative permittivity and a sufficiently low dielectric loss tangent in the millimeter-wave band, and shows minimal change in thickness before and after the curing process by heating and pressing. [Solution] A resin composition containing a reactive polymer and a filler, wherein the relative permittivity at 10 GHz when the adhesive layer made of the resin composition is completely cured is 5.0 or more, the dielectric loss tangent at 10 GHz is 0.01 or less, the difference between the maximum and minimum values ​​selected from a plurality of relative permittivity measurements in the range of 10 GHz to 80 GHz is 1.0 or less, the difference between the maximum and minimum values ​​selected from a plurality of dielectric loss tangent measurements in the range of 10 GHz to 80 GHz is 0.004 or less, and the rate of change in the thickness of the adhesive layer, determined based on the thickness of the adhesive layer made of the resin composition before curing by heat pressing and the thickness after the adhesive layer is completely cured, is 36% or less.

Description

Technical Field

[0001] The present invention relates to a resin composition, a laminate, a coverlay film, an adhesive sheet, a metal foil with resin, a metal-clad laminate, a printed wiring board, a semiconductor device, and a method for producing a resin composition.

Background Art

[0002] In recent years, with the miniaturization and high functionality of electronic components, higher density mounting has been required for wiring boards. Similarly, for mounted components, miniaturization, thinning, and high density are also required.

[0003] In response to such requirements, attention has been paid to the reduction of component-integrated substrates and antenna circuits using high dielectric constant insulating layers.

[0004] As such a high dielectric constant insulating layer, for example, as shown in Patent Documents 1 and 2, those in which an inorganic oxide having a high relative dielectric constant is highly filled as a filler are known.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, conventional high-dielectric-constant insulating layers, as described above, have not been adequately studied for their dielectric properties in the millimeter-wave band, for example, the high-frequency band of 28 GHz or higher, which has seen increasing demand in recent years as a frequency band for fifth-generation mobile communication systems. Therefore, the inventors of this invention have diligently studied this point and have found that the dielectric properties vary greatly depending on the frequency, depending on the composition of the resin composition forming the high-dielectric-constant insulating layer. Furthermore, when the aforementioned resin composition is used, for example, to form a high-dielectric-constant insulating layer on a substrate such as a printed circuit board, it is important that the impedance is expressed as designed when designing a circuit using this substrate.

[0007] The present invention has been made in view of the above problems, and aims to provide a resin composition that can be used in coverlay films, adhesive sheets, resin-coated metal foils, metal-clad laminates, or printed circuit boards, etc., which stably exhibits a sufficiently high relative permittivity and a sufficiently low dielectric loss tangent over a wide frequency range including the millimeter wave band (for example, 10 GHz to 80 GHz). Furthermore, the inventors considered that the unpredictable variations in signal transmission characteristics such as impedance in conventional high-dielectric-constant insulating layers might be due to changes in the thickness of the high-dielectric-constant insulating layer before and after the curing process by heating and pressing. [Means for solving the problem]

[0008] In other words, the present invention is as follows: [1] A resin composition containing a reactive polymer and a filler, The adhesive layer made of the resin composition has a relative permittivity of 5.0 or more at 10 GHz when fully cured, and a dielectric loss tangent of 0.01 or less at 10 GHz. The difference between the maximum and minimum values ​​of the relative permittivity selected from among several relative permittivity measurements taken in the range of 10 GHz to 80 GHz is 1.0 or less. The difference between the maximum and minimum values ​​of the dielectric loss tangent selected from among several dielectric loss tangents measured in the range of 10 GHz to 80 GHz is 0.004 or less. A resin composition wherein the rate of change in the thickness of the adhesive layer, which is determined based on the thickness of the adhesive layer made of the resin composition before curing by heat pressing and the thickness of the adhesive layer after it has been completely cured, is 36% or less. [2] The resin composition according to [1], wherein the filler is a paraelectric material. [3] The resin composition according to [1] or [2], further comprising an epoxy compound. [4] The resin composition according to any one of [1] to [3], wherein the content of the filler is 50 parts by mass or more per 100 parts by mass of the solid content of the resin composition. [5] A resin composition according to any one of [1] to [4], further containing an epoxy compound, wherein the content of the epoxy compound is 1 part by mass or more and 30 parts by mass or less per 100 parts by mass of the organic component contained in the resin composition, wherein the organic component is the component of the solid matter (solid content) of the resin composition excluding the filler. [6] The resin composition according to any one of [1] to [5], wherein the filler is a perovskite-type composite oxide (excluding barium titanate). [7] The resin composition according to any one of [1] to [6], wherein the average primary particle size of the filler is 0.1 μm or more and 1.0 μm or less, and the filler comprises at least one of strontium titanate and calcium titanate. A laminate comprising an adhesive layer formed from a resin composition described in any one of items [8][1] to [7], and a substrate in contact with at least one surface of the adhesive layer, A laminate in which the substrate is formed from one or more materials selected from the group consisting of resin, release resin, paper, release paper, and metal. A coverlay film, adhesive sheet, resin-coated metal foil, or metal-clad laminate comprising the laminate described in [9][8]. A printed circuit board comprising the laminate described in

[10] [8], or the coverlay film, adhesive sheet, resin-coated metal foil, or metal-clad laminate described in

[10] . A semiconductor device comprising the printed circuit board described in

[11]

[10] .

[12] Contains a reactive polymer and a filler, The adhesive layer made of the resin composition has a relative permittivity of 5.0 or more at 10 GHz when fully cured, and a dielectric loss tangent of 0.01 or less at 10 GHz. The difference between the maximum and minimum relative permittivity values ​​selected from among several relative permittivity values ​​measured in the range of 10 GHz to 80 GHz is 1.0 or less. The difference between the maximum and minimum dielectric loss tangents selected from among several dielectric loss tangents measured in the range of 10 GHz to 80 GHz is 0.004 or less. A method for producing a resin composition in which the rate of change in the thickness of the adhesive layer, determined based on the thickness of the adhesive layer made of the resin composition before curing by heat pressing and the thickness of the adhesive layer after it has been completely cured, is 36% or less, A mixing step of mixing the reactive polymer and the filler, A method for producing a resin composition, comprising a kneading step of kneading the mixture obtained by the mixing step.

[13] The method for producing a resin composition according to

[12] , wherein the mixing step involves mixing the mixture using a bead mill. [Effects of the Invention]

[0009] According to the present invention, the resin composition has a relative permittivity of 5.0 or more at 10 GHz in a fully cured state, a dielectric loss tangent of 0.01 or less at 10 GHz, a difference between the maximum and minimum values ​​of relative permittivity selected from a plurality of relative permittivity measured in the range of 10 GHz to 80 GHz is 1.0 or less, and a difference between the maximum and minimum values ​​of dielectric loss tangent selected from a plurality of dielectric loss tangents measured in the range of 10 GHz to 80 GHz is 0.004 or less. Furthermore, since the rate of change in the thickness of the adhesive layer, which is determined based on the thickness of the adhesive layer made of the resin composition before curing by heat pressing and the thickness after the adhesive layer has been completely cured, is set to 36% or less, it is possible to provide a resin composition that stably exhibits a sufficiently high relative permittivity and a sufficiently low dielectric loss tangent in a wide frequency band including the millimeter wave band (for example, 10 GHz to 80 GHz), and that exhibits small changes in thickness before and after the curing process by heat pressing when used as an adhesive layer. By using this resin composition, it is possible to provide coverlay films, adhesive sheets, resin-coated metal foils, metal-clad laminates, or printed circuit boards that stably exhibit a sufficiently high relative permittivity and a sufficiently low dielectric loss tangent in a wide frequency band including 10 GHz to 80 GHz, and that exhibit small changes in thickness before and after the curing process by heat pressing. [Modes for carrying out the invention]

[0010] The following describes specific examples of the resin composition, laminate, coverlay film, adhesive sheet, resin-coated metal foil, metal-clad laminate, printed circuit board, and semiconductor device according to the present invention. However, the present invention is not limited to these examples, and various modifications and combinations are possible without altering the spirit of the invention.

[0011] 1.Resin composition The resin composition according to this embodiment contains a reactive polymer and a filler. The components of the resin composition will be described below. In this embodiment, the resin composition includes a slurry obtained by dissolving or suspending the above-mentioned components in a solvent such as an organic solvent, or the slurry in a state obtained by applying this slurry to a substrate such as release paper and drying it (before heating), or the state after heating (partially cured or completely cured).

[0012] <Reactive polymer> As the reactive polymer in this embodiment, various polymers can be used without particular limitation as long as they do not significantly impair the required performance of a resin composition containing the reactive polymer, a printed wiring board manufactured using the resin composition, or the like.

[0013] From the viewpoint of being able to make the dielectric loss tangent of the resin composition as low as possible, it is preferable to use a reactive polymer having a low dielectric loss tangent. Specifically, the dielectric loss tangent in a wide frequency band of 10 GHz or more and 80 GHz or less is preferably 0.008 or less for the reactive polymer alone, more preferably 0.005 or less, still more preferably 0.003 or less, and particularly preferably 0.002 or less.

[0014] Examples of the reactive polymer as described above include resins having organic functional groups. From the viewpoint of improving heat resistance, the reactive polymer preferably has two or more organic functional groups in its molecule.

[0015] Specific examples of such reactive polymers include acrylic resins, phenoxy resins, polyamide resins, polyimide resins, polyester resins, polyphenylene oxide resins, polyurethane resins, polyacetal resins, polyolefin resins, styrene-based elastomers, and other thermoplastic elastomers. Among these, from the viewpoints of heat resistance and dielectric loss tangent, it is preferable to use polyimide resins, polyester resins, polyolefin resins, and styrene-based elastomers, and polyimide resins, polyolefin resins, and styrene-based elastomers are more preferable.

[0016] A polyimide resin is a resin having an imide ring as a repeating unit in the resin skeleton. The polyimide resin can be produced by various known methods. For example, a monomer group containing an aromatic tetracarboxylic acid anhydride and a diamine containing a dimer diamine or the like is preferably subjected to a polyaddition reaction at a temperature of about 60 to 120 °C, more preferably about 80 to 100 °C, preferably for about 0.1 to 2 hours, more preferably for about 0.1 to 0.5 hours, to obtain a polyadduct. The obtained polyadduct is preferably subjected to an imidization reaction, that is, a dehydration ring-closure reaction, at a temperature of about 80 to 250 °C, more preferably about 100 to 200 °C, preferably for about 0.5 to 50 hours, more preferably for about 1 to 20 hours, and can be produced by a method including such steps. In the step of the imidization reaction, various known reaction catalysts and dehydrating agents can be used. As the reaction catalyst, for example, an aliphatic tertiary amine such as triethylamine, an aromatic tertiary amine such as dimethylaniline, a heterocyclic tertiary amine such as pyridine, picoline, isoquinoline, etc. can be used. Further, as the dehydrating agent, for example, an aliphatic acid anhydride such as acetic anhydride or an aromatic acid anhydride such as benzoic anhydride can be used. The imide ring-closure ratio of the polyimide resin is not particularly limited. Here, the imide ring-closure ratio refers to the content of the cyclic imide bond in the polyimide resin and can be measured by, for example, NMR, IR analysis, etc. From the viewpoint of good adhesion and heat resistance, the imide ring-closure ratio of the polyimide resin is preferably about 70% or more, more preferably about 85 to 100%. Examples of such polyimide resins that can be used include commercially available products such as "SN20" and "PN20" from the "Ricacoat®" series and "MTA-15" from the "Ricacid®" series manufactured by Shin Nippon Rika Co., Ltd., "AD001," "AD002," and "NA001" from the "Spixeria®" series manufactured by Somar Co., Ltd., "100H," "100L," "130H," "150H," "150L," "200," "300," "600," "152H," and "252" from the "PIAD®" series manufactured by Arakawa Chemical Industries, Ltd., and the "U-Imide®" series manufactured by Unitika Ltd. These polyimide resins may be used individually or in combination of two or more types.

[0017] Polyester resin is a resin that has an ester skeleton as a repeating unit in its resin backbone. Examples of polyester resins include the "Byron®" series manufactured by Toyobo MC Co., Ltd., such as "200" (Mn: 17000, Tg: 67℃, hydroxyl value: 6mgKOH / g, acid value: 2mgKOH / g), "220" (Mn: 3000, Tg: 53℃, hydroxyl value: 50mgKOH / g, acid value: <2mgKOH / g), "226" (Mn: 8000, Tg: 65℃, hydroxyl value: 20mgKOH / g, acid value: <2mgKOH / g), "296" (Mn: 14000, Tg: 71℃, hydroxyl value: 7mgKOH / g, acid value: 6mgKOH / g), and "550" ( Mn: 28000, Tg: -15℃, Hydroxyl value: 4mgKOH / g, Acid value: <2mgKOH / g), "560" (Mn: 3000, Tg: 7℃, Hydroxyl value: 8mgKOH / g, Acid value: <2mgKOH / g), "822" (Mn: 15000, Tg: 68℃, Hydroxyl value: 3mgKOH / g, Acid value: 5mgKOH / g), "GK150" (Mn: 13000, Tg: 20℃, Hydroxyl value: 7mgKOH / g, Acid value: 5mgKOH / g), "GK150" (Mn: 13000, Tg: 20℃, Hydroxyl value: 7mgKOH / g, Acid value: 5mgKOH / g), "GK360 "GK570" (Mn: 19000, Tg: 0℃, hydroxyl value: 6mgKOH / g, acid value: <2mgKOH / g), "GK780" (Mn: 11000, Tg: 36℃, hydroxyl value: 11mgKOH / g, acid value: 3mgKOH / g), "GK810" (Mn: 6000, Tg: 46℃, hydroxyl value: 19mgKOH / g, acid value: 5mgKOH / g), "BX1001" (Mn: 28000, Tg: -18℃, hydroxyl value: 8mgKOH / g, acid value: 2mgKOH / g) ), Mitsubishi Chemical Corporation's "Tefablock" series "XLP0013", "Nichigo Polyester" series "TP-217" (Tg: 40℃, hydroxyl value: <7mgKOH / g, acid value: <3mgKOH / g), "TP-220" (Tg: 70℃, hydroxyl value: 3~8mgKOH / g, acid value: <3mgKOH / g), "TP-290" (Tg: 10℃, hydroxyl value: 2~6mgKOH / g, acid value: <4mgKOH / g), "LP-011" (Tg: 4℃, hydroxyl value: 4~8mgKOH / g, acid value: <3mgKOH / g), "LP-033" (Tg: 15℃,Commercially available polyester resins with a hydroxyl value of 4-8 mgKOH / g and an acid value of <1 mgKOH / g can be used. These polyester resins may be used individually or in combination of two or more types. Here, Mn is the number-average molecular weight and Tg is the glass transition temperature. The number-average molecular weight (Mn) can be measured by methods such as gel permeation chromatography (GPC). The glass transition temperature (Tg) can be measured by methods such as thermomechanical analysis (TMA) and differential scanning calorimetry (DSC). For example, it can be measured by DSC in accordance with the method specified in JIS K 7121.

[0018] Polyolefin resins are not particularly limited, but examples include homopolymers of olefin monomers such as ethylene, propylene, 1-butene, butadiene, isoprene, 1-hexene, and 1-octene; copolymers of olefin monomers; copolymers of olefin monomers; copolymers of olefin monomers and other monomers; and polymers mainly consisting of a hydrocarbon backbone, such as hydrides and halides of the resulting polymers. Among these polyolefin resins, polypropylene resin, which is a copolymer of propylene and other monomers, is preferred. Among the other monomers, olefin monomers are preferred, and ethylene or 1-butene are more preferred. Examples of such polyolefin resins include the "Admer®" series and "Unistoll®" series from Mitsui Chemicals, Inc., the "Aurolene®" series ("150A", "200S", "200T", "350S", "500T", "AE201", "AE301") from Nippon Paper Industries Ltd., the "Fusabond®" series ("P353", "P613", "E226", "A560") from Dow Chemical Ltd., the "Yumex®" series from Sanyo Chemical Industries Ltd., the P-type of the "Modic®" series from Mitsubishi Chemical Corporation, and the "Toyotac®" series ("M-100", "M-300") from Toyobo Co., Ltd. Products such as "M-310", "PMAH1000A", "PMAH1100A", "PMAH3000A", "PMA-T", "PMA-F2", and "PMA-L" from the "Hardlen (registered trademark)" series, "TD-15B", "NS-2002", "NS-2104", "MS-003K", "MS-003JD", and "SW-2420" from the "Hyros-X (registered trademark)" series manufactured by Seikoh PMC Co., Ltd., "PL-2051", "PL-2291", "QL-2251", "RL-2027", and "RL-2047" from the "Rikeaid (registered trademark)" series manufactured by Riken Vitamin Co., Ltd., and "MG-250P", "MG-400P", and "MG-670P" from the "Rikeaid (registered trademark)" series can be used. These polyolefin resins may be used individually or in combination of two or more types.

[0019] The styrene-based elastomer is preferably a copolymer mainly consisting of a block and / or random structure of an aromatic vinyl compound and a conjugated diene compound. The aromatic vinyl compound is not particularly limited, but examples include styrene, t-butylstyrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N,N-diethyl-p-aminoethylstyrene, vinyltoluene, and p-tertiary butylstyrene. Examples of the conjugated diene compound include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene. Specific examples of copolymers of aromatic vinyl compounds and conjugated diene compounds include styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), and styrene-ethylene-ethylene·propylene-styrene block copolymer (SEEPS). Examples of commercially available styrene-based elastomers that can be used include the "Toughprene®" series and "Asaprene® T" series from Asahi Kasei Corporation, the "Krayton® DSBS" series (SBS resin) from Kraton Polymer Japan Co., Ltd., the "Toughtech® H" series and "Toughtech® P" series from Asahi Kasei Corporation, the "Krayton® A" series, the "Krayton® E" series and "Krayton® G" series (SEBS resin) from Kraton Polymer Japan Co., Ltd., the "Toughtech® M" series from Asahi Kasei Corporation, and the "Krayton® FG" series (acid-modified SEBS resin) from Kraton Polymer Japan Co., Ltd. These styrene-based elastomers may be used individually or in combination of two or more types.

[0020] Furthermore, one of the aforementioned reactive polymers may be used as the reactive polymer, or a combination of multiple types may be used. For example, by including a polyimide resin, a resin composition with excellent heat resistance and adhesion and low dielectric loss tangent can be obtained. Also, by including a polyolefin resin and a styrene-based elastomer, a resin composition with excellent flexibility and low dielectric loss tangent can be obtained, which is preferable. Moreover, by using two or more of these reactive polymers, a resin composition with excellent flexibility, heat resistance, adhesion and low dielectric loss tangent can be obtained.

[0021] The weight-average molecular weight (Mw) of the reactive polymer is not particularly limited, but is preferably in the range of 20,000 to 180,000. A weight-average molecular weight of 20,000 or more is preferable because it increases the cohesive force of the cured resin composition, resulting in excellent adhesion. Furthermore, a weight-average molecular weight of 180,000 or less is preferable because it improves the fluidity and wettability of the resin composition, which can be expected to improve adhesion after curing and further improve solder heat resistance. The weight-average molecular weight (Mw) can be measured by gel permeation chromatography (GPC) or the like.

[0022] From the viewpoint of suppressing contamination of surrounding materials by gas components generated during heating (hereinafter also referred to as outgassing components), and, for example, when used as a high dielectric constant insulating layer on a substrate such as a printed circuit board, suppressing effects such as delamination and deformation of the insulating layer due to outgassing components generated during solder reflow processes and hot bar bonding processes, thereby improving adhesion and insulating reliability, it is preferable to use a reactive polymer with a low water absorption rate. Specifically, a water absorption rate of 1% or less, more preferably 0.5% or less, and even more preferably 0.3% or less, as measured according to IPC-TM-650, No.2.6.2.1, is preferred.

[0023] The organic functional group is not particularly limited as long as it satisfies the aforementioned performance requirements, but specific examples include carboxyl groups, acid anhydride groups, amino groups, hydroxyl groups, epoxy groups, mercapto groups, vinyl groups, acryloyl groups, and methacrylic groups. Among these, carboxyl groups, acid anhydride groups, amino groups, hydroxyl groups, and epoxy groups are preferred, with carboxyl groups or acid anhydride groups being more preferred. These organic functional groups may be present individually or in combination of two or more.

[0024] Various known methods can be used to produce the resin having the organic functional group. Examples include a method of copolymerizing by adding a compound having an organic functional group as a monomer, or a method of grafting a compound having an organic functional group onto a polymer. The method of grafting a compound having an organic functional group onto a polymer is preferred. Resins having a carboxyl group or an acid anhydride group are also called acid-modified resins. Here, the acid value of the acid-modified resin is preferably 0.5 mg / KOH or more and 30 mg / KOH or less, and more preferably 1 mg / KOH or more and 20 mg / KOH or less. By setting the acid value to 0.5 mg / KOH or more and 30 mg / KOH or less, the reactivity of the resin composition can be increased, and the heat resistance and insulation reliability after curing can be improved. The acid value is the number of milligrams of potassium hydroxide required to neutralize the acid groups (carboxyl groups, acid anhydride groups, etc.) contained in 1 g of resin, and can be measured, for example, in accordance with JIS K0070.

[0025] The content of the reactive polymer in the resin composition is preferably 50 parts by mass or more and 99 parts by mass or less, more preferably 60 parts by mass or more and 97 parts by mass or less, and even more preferably 70 parts by mass or more and 95 parts by mass or less, based on 100 parts by mass of the organic components contained in the resin composition. Here, the organic components refer to the components excluding fillers among the solid matter (solid content) of the resin composition that remains after the solvent such as an organic solvent has been completely evaporated from the resin composition.

[0026] The content of the organic component containing the reactive polymer in the resin composition according to this embodiment is preferably 1 part by mass or more and 50 parts by mass or less, and more preferably 5 parts by mass or more and 40 parts by mass or less, based on 100 parts by mass of the solid matter (solid content) of the resin composition that remains after the solvent such as an organic solvent has been completely evaporated from the resin composition.

[0027] <Filler> In this embodiment, the filler is made of an inorganic material, and it is preferable that the relative permittivity of the filler alone is 10 or more. More preferably, it is a so-called high-dielectric-constant filler in which the relative permittivity of the filler alone is 10 or more, and more preferably 100 or more, over a wide frequency band of 10 GHz to 80 GHz.

[0028] Specific examples of such fillers include titanium dioxide, barium oxide, barium titanate, magnesium titanate, strontium titanate, calcium titanate, magnesium zirconate, strontium zirconate, bismuth titanate, zirconium titanate, zinc titanate, barium zirconate, calcium zirconate titanate, lead zirconate titanate, barium magnesium niobate, and calcium zirconate. One of these fillers may be used alone, or multiple types may be used in combination.

[0029] The filler used in this embodiment is preferably a perovskite-type composite oxide. Furthermore, the filler is preferably a paraelectric material, from the viewpoint of exhibiting stable dielectric properties over a wide frequency band. In this embodiment, a paraelectric material refers to a compound that exhibits a paraelectric phase at room temperature (for example, 25°C).

[0030] In general, perovskite-type composite oxides in the paraelectric phase do not exhibit macroscopic polarization when no electric field is applied, as the centers of gravity of the cations and anions coincide. On the other hand, perovskite-type composite oxides in the ferroelectric phase generally exhibit spontaneous polarization in the absence of an electric field due to the misalignment of the centers of gravity of the cations and anions, which acts as orientation polarization. The microwave to millimeter-wave band is a region where the influence of orientation polarization shifts from being dominant to being dominated by ionic polarization; therefore, the dielectric properties of the ferroelectric phase in the millimeter-wave band are prone to instability. For this reason, it is more preferable to use perovskite-type composite oxides in the paraelectric phase as fillers. Examples of fillers that satisfy these properties include strontium titanate and calcium titanate.

[0031] The shape of the filler may be spherical, cubic, plate-like, fibrous, or irregular. There are no particular restrictions on the particle size of the filler, but in order to cope with the miniaturization and high density of printed circuit boards in recent years, it is preferable that the average primary particle size is on the nano-order to the submicron order (less than 1.0 μm). Specifically, it is preferable that the average primary particle size is 0.01 μm or more and 50 μm or less, more preferably 0.01 μm or more and 30 μm or less, even more preferably 0.05 μm or more and 10 μm or less, and particularly preferably 0.1 μm or more and less than 1.0 μm. By setting the average primary particle size of the filler to 0.1 μm or more and less than 1.0 μm, it is expected that the dispersibility of the filler in the resin composition will be further improved, and the uniformity of the thickness of the adhesive layer, as described later, will be further enhanced. The average primary particle size of the filler can be measured by dynamic light scattering (DLS), laser diffraction scattering (LD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), or calculation from the BET specific surface area. For example, it can be calculated by assuming that the particle shape is spherical, based on the specific surface area of ​​the particles measured by the BET flow method using a specific surface area measuring device. The filler may be untreated or may be pre-treated with a dispersant or the like, as described later.

[0032] The filler content in the resin composition is preferably 50 parts by mass or more and 99 parts by mass or less, more preferably 60 parts by mass or more and 95 parts by mass or less, and even more preferably 70 parts by mass or more and 90 parts by mass or less, per 100 parts by mass of solid content of the resin composition. By setting the filler content within the above range, the dielectric constant of the resin composition can be increased, and it is preferable because it can be provided with sufficient performance for purposes such as component-embedded substrates and shortening of antenna circuits that utilize a high dielectric constant insulating layer.

[0033] <Epoxy compounds> Epoxy compounds react with the organic functional groups in the reactive polymers described above to form a three-dimensional crosslinked structure, thereby exhibiting excellent adhesion to the adherend, high heat resistance to withstand the mounting process, and long-term insulation reliability. Therefore, it is preferable that the resin composition according to this embodiment contains an epoxy compound. In this embodiment, the case in which an epoxy compound is added separately from the reactive polymer described above is explained below, but the reactive polymer having epoxy groups may also function as the epoxy compound.

[0034] The epoxy compound is preferably a compound having two or more epoxy groups in its molecule in order to form the crosslinked structure described above. Specific examples of epoxy compounds include biphenyl-type epoxy resins, naphthalene-type epoxy resins, naphthol-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, bisphenol AF-type epoxy resins, novolac-type epoxy resins, trisphenol-type epoxy resins, alicyclic epoxy resins, dicyclopentadiene-type epoxy resins, aliphatic epoxy resins, glycidylamine-type epoxy resins, glycidyl ester-type epoxy resins, heterocyclic epoxy resins, and the like. From the viewpoint of adjusting reactivity and dielectric loss tangent to an appropriate range, glycidylamine-type epoxy resins, naphthalene-type epoxy resins, alicyclic epoxy resins, dicyclopentadiene-type epoxy resins, and aliphatic epoxy resins are more preferred among these. Including nitrogen-containing compounds such as glycidylamine-type epoxy resins is preferable because it can enhance the stability of the dielectric properties. You may use only one of the epoxy compounds mentioned above, or you may use multiple types in combination.

[0035] Examples of the epoxy compounds include DIC Corporation's "EPICLON®" series: "HP-4032", "HP-4032H", "HP-4032D" (naphthalene-type epoxy resin), "HP-4770" (naphthalene-type bifunctional epoxy resin), "HP-4700", "HP-4710" (naphthalene-type tetrafunctional epoxy resin), "HP-5000", "HP-9900" (naphthalene skeleton-modified polyfunctional epoxy resin), "N-690" (cresol novolac-type epoxy resin), and "N-695" (cresol novolac-type epoxy resin). ), "HP-7200", "HP-7200L", "HP-7200H", "HP-7200HH", "HP-7200HHH" (dicyclopentadiene type epoxy resin), "EXA-1514" (bisphenol S type epoxy resin), "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP-6000" (naphthylene ether type epoxy resin), Nippon Kayaku Co., Ltd.'s "EPPN-502H" (trisphenol type epoxy resin), "NC-7000L" (naphthol novolac) Biphenyl epoxy resins, "NC-3000H", "NC-3000", "NC-3000L", "NC-3100" (biphenyl type epoxy resins), Nippon Steel & Sumitomo Metal Chemical Co., Ltd.'s "ESN475V" (naphthalene type epoxy resin), "ESN485" (naphthol novolac type epoxy resin), Mitsubishi Chemical Corporation's "YX4000H", "YL6121" (biphenyl type epoxy resins), "YX4000HK" (bixylenol type epoxy resin), "YX8800" (anthracene type epoxy resin), Osaka Gas Chemical Co., Ltd.'s "PG-100", "CG -500", Mitsubishi Chemical Corporation's "YL7800" (fluorene-type epoxy resin), Mitsubishi Chemical Corporation's "jER1010" (solid bisphenol A type epoxy resin), "jER1031S" (tetraphenylethane type epoxy resin), "jER827", "jER828", "jER834" (liquid bisphenol A type epoxy resin), Toyobo Co., Ltd.'s "AH-280", Mitsubishi Gas Chemical Co., Ltd.'s "TETRAD-C", "TETRAD-X" (tetrafunctional glycidylamine type epoxy resin), Daicel Corporation's "Epolid PB-3600",Products commercially available such as "Epolid PB-4700" (epoxidized polybutadiene) and "jERYX7760" (fluorine-containing epoxy resin) manufactured by Mitsubishi Chemical Corporation can be used.

[0036] The weight-average molecular weight (Mw) of the epoxy compound is not particularly limited, but is preferably in the range of 100 to 1000. This weight-average molecular weight allows for good heat resistance and adhesion of the cured resin composition. Furthermore, the epoxy equivalent of the epoxy compound is preferably in the range of 50 to 300. This range allows for a reduction in the reaction time of the resin composition, and also improves the crosslink density of the crosslinked structure formed by the reaction, thereby improving heat resistance. Here, epoxy equivalent refers to the weight of the epoxy compound containing one equivalent of epoxy groups, and can be measured by a method compliant with JIS K 7236.

[0037] The epoxy compound content in the resin composition is preferably 1 to 30 parts by mass, more preferably 3 to 25 parts by mass, and even more preferably 5 to 20 parts by mass, per 100 parts by mass of organic components contained in the resin composition. Keeping the epoxy compound content within the above range is preferable because it allows for the maintenance of sufficient crosslinking density and the expectation of improved adhesion and heat resistance. Furthermore, since the dielectric loss tangent tends to decrease as the epoxy compound content decreases, a resin composition with a lower dielectric loss tangent can be obtained by preferably setting the epoxy compound content to 30 parts by mass or less, and more preferably 20 parts by mass or less.

[0038] <Dispersant> In recent years, with the miniaturization and increased density of printed circuit boards, the particle size of the added fillers has tended to decrease, specifically, there has been an increase in the use of fillers on the nano-order to submicron-order, as mentioned above. Fillers with such small particle sizes have a large specific surface area, and the cohesive force between fillers increases, making it difficult to disperse them uniformly. Therefore, in order to improve the dispersibility of the fillers in the resin composition, the resin composition may further contain a dispersant.

[0039] The dispersant used in this embodiment is not particularly limited as long as it can improve the dispersibility of the filler in the resin composition described above, but specific examples include wetting dispersants, surfactants, silane coupling agents, titanium coupling agents, etc. Among these, the use of a wetting dispersant is preferred.

[0040] A wetting dispersant is a compound consisting of a polymer unit (containing hydrophobic groups) that has affinity for a medium such as a resin, and a polar functional group unit (containing hydrophilic groups) that has affinity for a filler. When a wetting dispersant is adsorbed onto the filler surface, electronic repulsion and steric hindrance act between the fillers, inhibiting the aggregation of the fillers. Therefore, dispersibility can be improved even for fillers on the nano-order to submicron-order.

[0041] When a resin composition contains a dispersant, there are no particular restrictions on the amount of dispersant, as long as it does not significantly impair the required performance of the resin composition for use in printed circuit boards, etc. However, for example, it is preferable that the amount of dispersant be 0.01 parts by mass or more and 1 part by mass or less per 100 parts by mass of filler, more preferably 0.01 parts by mass or more and 0.5 parts by mass or less, and even more preferably 0.01 parts by mass or more and 0.3 parts by mass or less. It is preferable that the amount of dispersant be within the above range, as this not only provides a sufficient dispersibility improvement effect, but also suppresses a decrease in heat resistance and deterioration of dielectric loss tangent, and further suppresses gelation due to reaction with reactive polymers and epoxy compounds.

[0042] In addition to those mentioned above, the resin composition of this embodiment may also contain (poly)carbodiimide, light absorbers, organic solvents, etc., to the extent that they do not affect the performance of the resin composition.

[0043] (Poly)carbodiimide is a nitrogen-containing compound having carbodiimide bonds. (Poly)carbodiimide can improve adhesion by increasing the interaction between the resin composition and the substrate through the reaction of the carbodiimide groups with functional groups such as hydroxyl groups, amino groups, and carboxyl groups present in the aforementioned reactive polymers. Such (poly)carbodiimides are commercially available, including the "Carbodilite®" series manufactured by Nisshinbo Chemical Inc. The content of (poly)carbodiimide in the resin composition is preferably 0.01 parts by mass to 10 parts by mass, more preferably 0.03 parts by mass to 5 parts by mass, and even more preferably 0.1 parts by mass to 3 parts by mass, per 100 parts by mass of solid content of the resin composition. It is preferable to keep the (poly)carbodiimide content within the above range because it is possible to achieve both stable dielectric properties and adhesion over a wide frequency band.

[0044] The light absorber is not particularly limited, and any material capable of absorbing irradiated light can be used. The wavelength range of the light to be absorbed is preferably 200 nm to 10.6 μm, more preferably 200 nm to 1100 nm, and even more preferably 200 nm to 450 nm. Here, the wavelength range of 200 nm to 450 nm is generally called the ultraviolet region, and light absorbers that absorb wavelengths in this ultraviolet region are called ultraviolet absorbers. Examples of light absorbers include benzophenone derivatives, benzoate derivatives, benzotriazole derivatives, triazine derivatives, benzothiazole derivatives, cinnamate derivatives, anthranilate derivatives, and dibenzoylmethane derivatives. These may be used alone or in combination of two or more. The content of the light absorber is not particularly limited, but is preferably 0.01% to 1% by mass, more preferably 0.1% to 0.8% by mass, and even more preferably 0.2% to 0.5% by mass, per 100 parts by mass of the solid content of the resin composition. A light absorber content of 0.01% by mass or more is preferable because it is easier to prevent light transmission, and a content of 1% by mass or less is preferable because it is easier to suppress the bleed-out of the light absorber.

[0045] The workability of a resin composition can be improved by dissolving, dispersing, and diluting it with an organic solvent to form a solution (varnish) or slurry. The organic solvent is not particularly limited as long as it uniformly dissolves or disperses each component. Specifically, examples include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as hexane, heptane, octane, and decane; alicyclic hydrocarbons such as cyclohexane, cyclohexene, methylcyclohexane, and ethylcyclohexane; halogenated hydrocarbons such as trichloroethylene, dichloroethylene, chlorobenzene, and chloroform; alcoholic solvents such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, and phenol; acetone, methyl isobutyl ketone, methyl ethyl ketone, pentanone, hexanone, and cyclohexanone. Examples include ketone solvents such as isophorone and acetophenone, cellsolves such as methyl cellsolve and ethyl cellsolve, ester solvents such as methyl acetate, ethyl acetate, butyl acetate, methyl propionate, and butyl formate, and glycol ether solvents such as ethylene glycol mono-n-butyl ether, ethylene glycol mono-iso-butyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-iso-butyl ether, triethylene glycol mono-n-butyl ether, and tetraethylene glycol mono-n-butyl ether. These may be used individually or in combination of two or more. Low-polarity solvents such as aromatic hydrocarbons and aliphatic hydrocarbons are preferred from the viewpoint of solubility and the effect on the dielectric loss tangent when a very small amount remains.

[0046] When an organic solvent is added to a resin composition, from the viewpoint of workability, it is preferable that the content of the organic solvent be 3 parts by mass or more and 90 parts by mass or less per 100 parts by mass of the resin composition, and more preferably 10 parts by mass or more and 80 parts by mass or less. If the content of the organic solvent is 10 parts by mass or more and 80 parts by mass or less per 100 parts by mass of the resin composition, the viscosity of the solution (varnish) or slurry will be appropriate, and it will be easier to work with, which is preferable.

[0047] <Other Optional Components> In addition to the optional components mentioned above, the resin composition may further contain other optional components such as thermoplastic resins, tackifiers, flame retardants, curing agents, curing accelerators, reaction initiators, heat aging inhibitors, leveling agents, defoamers, pigments, etc.

[0048] As a curing agent, for example, commercially available epoxy resin curing agents that are generally used to cure epoxy resins can be used, and examples include amine-based curing agents and acid anhydride-based curing agents, but are not limited to these. Examples of amine-based curing agents include diethylenetriamine, triethylenetetramine, metaphenylenediamine, dicyandiamide, polyamidoamine, 3,3'-diphenyldiaminosulfone, 4,4'-diphenyldiaminosulfone, 4,4'-sulfonylbis(p-phenoxyaniline), methylated melamine resin, and benzoguanamine resin. Furthermore, examples of acid anhydride-based curing agents include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexane-1,2-dicarboxylic acid anhydride, trimellitic anhydride, pyro anhydride Examples include meritol acid, bensophenonetetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic acid dianhydride, 3,3'-4,4'-diphenylsulfonetetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-C]furan-1,3-dione, ethylene glycol bis(anhydrotrimellitate), etc. These curing agents may be used alone or in combination of two or more. Here, the optional curing agents do not include the reactive polymers, epoxy compounds, or (poly)carbodiimides mentioned above.

[0049] A curing accelerator is a compound that catalyzes and accelerates the curing reaction of a resin composition containing an epoxy compound. Examples of curing accelerators include one or more selected from the group consisting of tertiary amine curing accelerators, tertiary amine salt curing accelerators, and imidazole curing accelerators. By including a curing accelerator, for example, the reactivity of the reactive polymer and epoxy compound can be increased. On the other hand, from the viewpoint of maintaining the pot life and product life as long as possible when the resin composition is used as a varnish or a semi-cured (B-stage) adhesive layer as described later, it is preferable to reduce the amount of curing accelerator in the resin composition, preferably to an amount below that causes a decrease in pot life or product life, and curing accelerators may be omitted. Here, the curing accelerator, which is an optional component, does not include those corresponding to the reactive polymer, epoxy compound, and (poly)carbodiimide mentioned above.

[0050] If the resin composition of the present invention contains any components such as a thermoplastic resin, tackifier, flame retardant, curing agent, curing accelerator, reaction initiator, heat aging inhibitor, leveling agent, defoamer, or pigment, the total content of these optional components is preferably within a range that does not affect the function of the resin composition, that is, it may be 0 (not included at all) when the total resin composition is 100 parts by mass, or it may be greater than 0 and within a range of 20 parts by mass or less, 10 parts by mass or less, 5 parts by mass or less, or 1 part by mass or less.

[0051] The adhesive layers formed using the resin composition according to this embodiment, such as coverlay films, adhesive sheets, resin-coated metal foils, and metal-clad laminates, can be suitably used as materials for printed circuit boards, particularly for high-frequency signal transmission printed circuit boards, as described below.

[0052] <Method for producing the resin composition according to this embodiment> The resin composition of this embodiment can be manufactured by a mixing process that uniformly mixes each of the aforementioned components. To improve workability, the resin composition may be dissolved and diluted with an organic solvent as described above to form a solution (varnish) or slurry.

[0053] More specific methods for manufacturing resin compositions include thoroughly mixing predetermined amounts of raw materials using a mixer or dissolver, and then kneading the resulting mixture using a mixing roll, kneader, bead mill, ball mill, extruder, etc. Among these, kneading using a bead mill or ball mill is preferred, and kneading using a bead mill after thorough mixing with a dissolver is even more preferred. By using a bead mill for kneading, the dispersibility of fillers contained in the resin composition can be improved, thereby suppressing the formation of irregularities on the surface of the adhesive layer formed by the resin composition due to filler aggregates, and thus improvements in flexibility and thickness uniformity can be expected. In the process of heat-curing the adhesive layer by heating and pressing, if there are irregularities on the surface of the adhesive layer, the surface irregularities become smoother during the heating and pressing process, so the thickness of the adhesive layer after heating and pressing tends to be thinner than the thickness of the adhesive layer before heating and pressing, and the change in the thickness of the adhesive layer before and after heating and pressing tends to be large. Generally, impedance changes not only with the shape of the conductor portion of the circuit but also with the thickness of the insulating portion. Therefore, in a printed circuit board using an adhesive layer made of the resin composition as an insulating layer, it becomes difficult to achieve the impedance as designed if the thickness of the adhesive layer changes. On the other hand, by using a bead milling method, the dispersibility of the filler contained in the resin composition can be improved, and the formation of surface irregularities in the adhesive layer formed by the resin composition can be suppressed. As a result, the rate of change in the thickness of the adhesive layer before and after heating and pressing can be reduced, making it easier to achieve the impedance as designed in a printed circuit board using the resin composition. The processing conditions for the bead mill can be appropriately set considering the type of filler and reactive polymer contained in the resin composition, and the particle size of the filler. For example, the bead material, bead particle size, and processing time can be appropriately set. Examples of bead materials include ceramic, glass, and stainless steel. Glass beads are preferred from the viewpoint of availability and low cost. Ceramic beads such as alumina and zirconia are preferred from the viewpoint of ease of dispersion of high-hardness fillers. An example of more suitable mixing conditions by the bead mill is the following: The bead particle size is preferably 0.01 mm to 10 mm, more preferably 0.5 mm to 5 mm, and the processing time is preferably 1 minute to 300 minutes, more preferably 10 minutes to 60 minutes. The dispersion state of fillers in the resin composition and in laminates, coverlay films, adhesive sheets, resin-coated metal foils, metal-clad laminates, printed circuit boards, etc., formed using the resin composition can be measured by microscopic observation, dynamic light scattering (DLS), laser diffraction scattering (LD), etc. The obtained resin composition may be molded into shapes such as sheets or tablets, or coated onto a substrate by impregnation, coating, spraying, etc., as needed. If the resin composition is in the form of a solution (varnish) or slurry, the organic solvent may be removed by hot air drying after processing such as coating to obtain a resin composition.

[0054] 2.Cured product By thermal curing the resin composition of the present invention, a cured product is obtained that, for example, becomes an insulating layer and / or adhesive layer of a laminated substrate. Curing allows the resin composition to fully exhibit its performance and can be applied to desired uses such as printed circuit boards, as described later. In this embodiment, the thermal curing includes the following two steps.

[0055] When the resin composition is heated, covalent bonds first form two-dimensional crosslinking (molecular chain elongation) between the reactive polymer and the epoxy compound in the resin composition, resulting in a cured product in a semi-cured (B-stage) state.

[0056] By further heating this semi-cured product, covalent bonds that form three-dimensional crosslinks (inter-chain crosslinks) occur between the reactive polymer and the epoxidized compound, and between the epoxy compounds themselves, resulting in a fully cured (C-stage) product with a crosslinked structure.

[0057] These B-stage and C-stage materials can be distinguished, for example, by their solubility when immersed in a solvent such as an organic solvent.

[0058] The conditions for thermal curing to reach the fully cured (C stage) state are not particularly limited, and for example, conditions commonly used when forming the insulating layer of a printed circuit board may be used. For example, the curing conditions for the resin composition are such that the curing temperature is in the range of 80°C to 240°C, preferably in the range of 120°C to 220°C, more preferably in the range of 150°C to 200°C, and even more preferably in the range of 170°C to 190°C. The curing time can be 1 minute to 240 minutes, preferably 10 minutes to 180 minutes, more preferably 30 minutes to 120 minutes, and even more preferably 30 minutes to 90 minutes.

[0059] Furthermore, a heated press is typically used as a method for forming the insulating layer of a printed circuit board. The press pressure conditions are not particularly limited and can be those of any commonly used type. For example, a range of 0.5 MPa to 5 MPa, more preferably 1 MPa to 5 MPa, and even more preferably 2.5 MPa to 4.5 MPa can be adopted. From the viewpoint of more completely curing the resin composition, it is preferable to heat-press the resin composition for 30 minutes to 120 minutes at a heating temperature of 170°C to 190°C and a pressing pressure of 2.0 MPa to 5.0 MPa. Furthermore, by adding an after-cure step of heating within the above temperature range after heat-pressing, the cured resin composition can be brought closer to a more completely cured state. By completely curing the resin composition, improvements in the heat resistance and adhesive properties of the cured product can be expected.

[0060] The cured product of the C stage obtained by thermal curing the resin composition according to this embodiment exhibits a sufficiently high relative permittivity and a sufficiently low dielectric loss tangent over a wide frequency band of 10 GHz to 80 GHz. A sufficiently high relative permittivity is defined as a relative permittivity of 5 or higher at a measurement frequency of 10 GHz or higher, preferably 6 or higher, and more preferably 7 or higher. A sufficiently low dielectric loss tangent is defined as a dielectric loss tangent of 0.010 or less at a measurement frequency of 10 GHz or higher, preferably 0.008 or less, and more preferably 0.006 or less.

[0061] Furthermore, the criteria for the stability of dielectric properties (i.e., low frequency dependence of relative permittivity and dielectric loss tangent) in a wide frequency band from 10 GHz to 80 GHz are as follows. First, the criterion for stability regarding relative permittivity is the highest relative permittivity in the measurement frequency band (see this specification). The difference between the highest relative permittivity (also referred to as the "maximum relative permittivity" in this specification) and the lowest relative permittivity (also referred to as the "minimum relative permittivity" in this specification) is 1.0 or less, preferably 0.6 or less, more preferably 0.4 or less, and even more preferably 0.2 or less. Here, the measurement frequency of the highest relative permittivity only needs to be different from the measurement frequency of the lowest relative permittivity, and the relative magnitude relationship between the measurement frequency of the highest relative permittivity and the measurement frequency of the lowest relative permittivity is not particularly limited. For example, the measurement frequency of the highest relative permittivity (e.g., 80 GHz) may be greater than the measurement frequency of the lowest relative permittivity (e.g., 10 GHz). Alternatively, the measurement frequency of the highest relative permittivity (e.g., 10 GHz) may be less than the measurement frequency of the lowest relative permittivity (e.g., 80 GHz). Note that the measurement frequencies of the highest and / or lowest relative permittivity are not limited to one, and there may be two or more. The stability criterion for dielectric loss tangent is that the difference between the highest and lowest dielectric loss tangents in the measurement frequency band is 0.004 or less, preferably 0.003 or less, more preferably 0.002 or less, and even more preferably 0.001 or less.

[0062] Methods for measuring relative permittivity and dielectric loss tangent can be generally known, but specific examples include the resonator method, free-space method, coaxial / waveguide (reflection / transmission) method, coaxial probe method, and capacitance method. Among these, the resonator method, which offers excellent measurement reliability in the high-frequency band, is preferred.

[0063] The cured product of the C stage obtained by thermosetting the resin composition according to this embodiment preferably has a low water absorption rate, preferably 1% or less, more preferably 0.5% or less, and even more preferably 0.3% or less, from the viewpoint of suppressing the influence of outgassing components on surrounding components. If the water absorption rate is 1% or less, contamination of surrounding components by outgassing components generated during heating can be suppressed. Furthermore, for example, when used as a high dielectric constant insulating layer on a substrate such as a printed circuit board, it is possible to suppress the effects of outgassing components generated during processes such as solder reflow and hot bar bonding, such as delamination and deformation of the insulating layer, thereby improving adhesion and insulating reliability.

[0064] 3. Laminate The resin composition according to this embodiment may be used, for example, to form a laminate comprising an adhesive layer formed from this resin composition and a substrate in contact with at least one surface of the adhesive layer. This laminate may be prepared in a semi-cured (B-stage) state in which only a portion of the resin composition has hardened by applying the resin composition to the substrate, drying it, and then primary heating it. The resulting laminate can also be bonded with another substrate to obtain a laminate having substrates on both sides of the adhesive layer. The laminate may be further subjected to secondary heating to fully harden the adhesive layer (C-stage).

[0065] In the laminate of this embodiment, the thickness of the adhesive layer is not particularly limited, but is preferably 1 μm to 300 μm, more preferably 5 μm to 200 μm, and even more preferably 5 μm to 150 μm. By setting the thickness of the adhesive layer to 5 μm or more, good adhesion is easily achieved, surface irregularities caused by fillers are less likely to occur, and an adhesive layer with high thickness uniformity is easily obtained. By setting the thickness of the adhesive layer to 200 μm or less, when the resin composition contains an organic solvent, it is possible to reduce the amount of organic solvent remaining in the drying process.

[0066] The adhesive layer can be formed, for example, by applying a resin composition to a substrate and drying it to remove the organic solvent. Examples of application methods include roll coating, reverse roll coating, transfer roll coating, gravure coating, gravure reverse coating, comma coating, rod coating, blade coating, bar coating, wire bar coating, die coating, lip coating, and dip coating. Examples of drying methods include known methods such as heating and hot air blowing. For example, a semi-cured (B-stage) adhesive layer can be formed by drying at a temperature of 80°C to 150°C for 3 to 5 minutes.

[0067] The adhesive layer of the laminate in this embodiment may comprise a first adhesive layer (also called the first adhesive layer) formed from the aforementioned resin composition, and a second adhesive layer (also called the second adhesive layer or stress relaxation layer) having a different composition from the first adhesive layer. For example, by forming a multilayer structure in which a stress relaxation layer is laminated between the first adhesive layer and the substrate, the flexibility and adhesion of the adhesive layer can be improved. In the laminate of this embodiment, the stress relaxation layer may be provided on the surface of the adhesive layer that is in contact with the substrate, on the surface of the adhesive layer that is not in contact with the substrate, or on both sides. Generally, increasing the amount of high dielectric constant filler added to increase the dielectric constant of the adhesive layer tends to decrease the flexibility and adhesion of the adhesive layer. Therefore, it is preferable that the adhesive layer has a multilayer structure with a stress relaxation layer, as this allows for the creation of a laminate that achieves both high dielectric constant and flexibility and adhesion of the adhesive layer.

[0068] The stress relaxation layer preferably contains a resin (also called a stress relaxation layer resin), and examples of such resins include acrylic resin, phenoxy resin, polyamide resin, polyimide resin, polyester resin, polycarbonate resin, polyphenylene oxide resin, polyurethane resin, polyacetal resin, polyolefin resin, styrene elastomer, and other thermoplastic elastomers. Among these, polyimide resin, polyester resin, polyolefin resin, and styrene elastomer are particularly preferred from the viewpoint of heat resistance and dielectric loss tangent, and polyimide resin, polyolefin resin, and styrene elastomer are more preferred. The resin may be the same as or different from the reactive polymer contained in the resin composition contained in the adhesive layer.

[0069] From the viewpoint of being able to lower the dielectric loss tangent of the stress relaxation layer, the resin included in the stress relaxation layer is preferably one in which the dielectric loss tangent in a wide frequency band of 10 GHz to 80 GHz is 0.008 or less, more preferably 0.005 or less, even more preferably 0.003 or less, and particularly preferably 0.002 or less.

[0070] The stress relaxation layer may contain a crosslinking agent, which is a component for crosslinking the resin for the stress relaxation layer. The crosslinking agent can be any component that reacts with and crosslinks the resin for the stress relaxation layer, such as epoxy compounds, isocyanate compounds, amine compounds, and acid anhydrides. When the adhesive layer has a multilayer structure including the stress relaxation layer, it is preferable that at least one of the resin or crosslinking agent contained in the stress relaxation layer has excellent compatibility with the reactive polymer contained in the resin composition forming the first adhesive layer, from the viewpoint of improving the interlayer adhesion between the first adhesive layer and the stress relaxation layer within the adhesive layer.

[0071] The stress-relieving layer can be formed, for example, by adding the crosslinking agent and organic solvent as needed to the resin for the stress-relieving layer to form a varnish, applying it to a substrate, and drying it to remove the organic solvent. Examples of application methods include roll coating, reverse roll coating, transfer roll coating, gravure coating, gravure reverse coating, comma coating, rod coating, blade coating, bar coating, wire bar coating, die coating, lip coating, and dip coating. The method for manufacturing the adhesive layer including the stress-relieving layer is not particularly limited, but after forming the stress-relieving layer, a resin composition may be applied and dried on top of it to form the first adhesive layer. Alternatively, after forming the first adhesive layer made of the resin composition, a resin for forming the stress-relieving layer may be applied and dried on top of it. Furthermore, after forming the stress-relieving layer as an independent sheet, this stress-relieving layer may be laminated to one or both sides of the first adhesive layer, which has been separately formed as a sheet, using a roll lamination method or a vacuum lamination method.

[0072] The thickness of the stress relaxation layer is not particularly limited, but is preferably 0.1 μm to 10 μm, more preferably 1 μm to 8 μm, and even more preferably 3 μm to 7 μm. The ratio of the thickness of the stress relaxation layer to the total thickness of the adhesive layer (stress relaxation layer / adhesive layer) is preferably 0.01 to 99. A stress relaxation layer thickness of 1 μm or more makes it easier to achieve good bendability and adhesion. A stress relaxation layer thickness of 8 μm or less makes it easier to maintain a high dielectric constant of the adhesive layer.

[0073] The stress relaxation layers described above can also be applied to coverlay films, adhesive sheets, resin-coated metal foils, metal-clad laminates, printed circuit boards, and semiconductor devices equipped with these, as will be described later.

[0074] In this embodiment, the adhesive layer preferably has high adhesion. An adhesive layer with excellent adhesion can improve insulation reliability and solder heat resistance. The adhesion of the adhesive layer can be evaluated, for example, by peel strength, and a preferred range for peel strength is, for example, 0.1 N / mm or more, preferably 0.3 N / mm or more, more preferably 0.6 N / mm or more, and even more preferably 1.0 N / mm or more. The peel strength can be measured in the same manner as shown in the examples.

[0075] In this embodiment, from the viewpoint of improving impedance stability, it is preferable that the adhesive layer has high uniformity in thickness. For example, it is preferable that the change in thickness before and after heating press is small. If there is a large variation in the thickness of the adhesive layer, the impedance variation in the printed circuit board having this adhesive layer tends to be large, which can cause noise generation. Therefore, it is preferable that the thickness of the adhesive layer is highly uniform. Furthermore, when using an adhesive layer made of a conventional resin composition, the impedance changes from the circuit design due to the change in the thickness of the adhesive layer before and after the heat curing process by heating press, resulting in the problem that the impedance cannot be expressed as designed. Therefore, the difference between the thickness of the adhesive layer before curing by heat pressing and the thickness after curing is preferably small, preferably 10 μm or less, more preferably 3 μm or less, and even more preferably 1 μm or less. The rate of change between the thickness of the adhesive layer before curing and the thickness after curing is preferably small, preferably 36% or less, more preferably 10% or less, and even more preferably 5% or less. Here, the rate of change in thickness can be measured in the same manner as shown in the examples. It is preferable to keep the rate of change in thickness within the above range because it makes it easier to stably exhibit the impedance as designed in the printed circuit board having the cured product after heat pressing of the adhesive layer.

[0076] Furthermore, in both the B-stage and C-stage states, the adhesive layer is preferably highly flexible, from the viewpoint of processability in the transport and lamination processes when manufacturing metal-clad laminates and printed circuit boards, as described later. By providing an adhesive layer with excellent flexibility, cracking and detachment of the adhesive layer during the transport and lamination processes can be suppressed, thereby reducing process contamination. In addition, an adhesive layer with excellent flexibility is preferable because it makes it easier to maintain the flexibility of metal-clad laminates and printed circuit boards. Methods for evaluating flexibility include wrapping the adhesive layer around a cylindrical tube or bending it 180 degrees and visually evaluating whether there are any cracks or detachments.

[0077] The performance of the adhesive layer described above is also suitable for use in coverlay films, adhesive sheets, resin-coated metal foils, metal-clad laminates, printed circuit boards, and semiconductor devices equipped therewith, as described later.

[0078] The type of substrate is not particularly limited, but any substrate commonly used for printed circuit boards may be used as appropriate. Examples of the aforementioned substrates include cloth, nonwoven fabric, or sheet-like substrates made of glass, glass fiber, organic fiber, metal, resin, paper, etc., or composite materials made by using multiple types of these materials in combination.

[0079] Specific examples of organic fiber substrates are not limited to those mentioned above, but include woven and nonwoven fabrics made from fibers such as polyester resin, polyamide resin, polyimide resin, polyamide-imide resin, liquid crystal polymer, polyphenylene sulfide, polyolefin resin, and fluororesin.

[0080] Specific examples of metal substrates include copper foil, aluminum foil, and SUS foil.

[0081] Specific examples of resin substrates include those made of polyester resin, polyamide resin, polyimide resin, polyamide-imide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, and fluororesin.

[0082] Specific examples of paper substrates include fine paper, kraft paper, roll paper, and glassine paper.

[0083] To transfer the adhesive layer to other substrates, release substrates can be used that have been treated with a release agent on the surface of the aforementioned resin substrate or paper substrate. Examples of such release agents include those containing silicone-based, fluorine-based, or alkyd-based release resins.

[0084] 4. Coverlay film In this embodiment, the coverlay film (CL) is a laminate having a B-stage adhesive layer formed of the aforementioned resin composition on a substrate with excellent insulating properties, and is difficult to separate from the substrate and the adhesive layer. The aforementioned resin substrate can be used as the substrate with excellent insulating properties. In addition, to protect the adhesive layer, a protective layer may be laminated on the surface of the adhesive layer that is not in contact with the substrate with excellent insulating properties. A release agent can be used as the protective layer. Laminating a protective layer on the adhesive layer allows for winding without the adhesive layer transferring to the substrate, resulting in excellent operability, as well as excellent storage properties and easy handling during use, which is preferable.

[0085] This coverlay film can function as an insulating coating material by peeling off the protective layer, making surface contact with the adhesive layer on any circuit board, and then heating and pressing it.

[0086] 5. Adhesive sheet In this embodiment, the adhesive sheet (bonding sheet, BS) is, for example, a laminate having an adhesive layer in a B-stage state formed of the resin composition described above on a release substrate as described above, and in which the adhesive layer can be isolated. To protect the adhesive layer, a release substrate may be laminated on both sides of the adhesive layer. The release substrate acts as a protective layer for the adhesive layer, allowing winding without the adhesive layer bleeding onto the substrate, resulting in excellent operability, and is preferable because it protects the adhesive layer, resulting in excellent storage properties and easy handling during use.

[0087] This adhesive sheet can function as an interlayer adhesive by peeling off one release substrate, transferring the adhesive layer to any substrate, peeling off the other release substrate, surface-bonding the adhesive layer to the substrate, and then heating and pressing it.

[0088] 6. Metal foil with resin coating In this embodiment, the resin-coated metal foil is a laminate having an adhesive layer in a B-stage state formed of the aforementioned resin composition on the aforementioned metal substrate, and is difficult to separate from the substrate and the adhesive layer. Furthermore, to protect the adhesive layer, a protective layer may be laminated on the surface of the adhesive layer that is not in contact with the metal substrate. The aforementioned release substrate can be used as the protective layer. Laminating a protective layer to the adhesive layer is preferable because it allows winding without transfer to the substrate, resulting in excellent operability, and because the adhesive layer is protected, it offers excellent storage properties and is easy to handle when in use.

[0089] This resin-coated metal foil can function as a circuit-forming material by removing the protective layer, bringing the adhesive layer into surface contact with any substrate or circuit board, and then heating and pressing it.

[0090] 7.Metal clad laminate In this embodiment, a metal-clad laminate is a laminate in which a metal substrate and a resin substrate are bonded together and integrated via an adhesive layer formed from the aforementioned resin composition. This metal-clad laminate can be manufactured, for example, by applying the aforementioned resin composition to one of the substrates (the metal substrate or the resin substrate), drying it, bonding it to the other substrate, and then completely curing it using an oven or the like. The adhesive layer and the metal substrate may be laminated on both sides of the resin substrate. A laminate in which the adhesive layer and the metal substrate are laminated on only one side of the resin substrate is called a single-sided metal-clad laminate, and a laminate in which the resin composition layer and the metal substrate are laminated on both sides of the resin substrate is called a double-sided metal-clad laminate.

[0091] This metal-clad laminate can function, for example, as a circuit-forming material for printed circuit boards.

[0092] 8. Printed circuit board In this embodiment, the printed circuit board includes a laminate formed from a metal substrate and a resin substrate as constituent elements, which form a conductor circuit. This printed circuit board can be manufactured by conventionally known methods, such as the subtractive method using the metal-clad laminate described above. If necessary, an insulating coating layer can be provided on the conductor circuit formed by the metal substrate, either partially or entirely, using a coverlay film or screen printing ink, thereby creating a so-called flexible circuit board (FPC), flexible flat cable (FFC), or circuit board for automated tape bonding (TAB). The insulating coating layer can be formed, for example, by using the coverlay film described above, by peeling off the release substrate of the coverlay film, laminating the adhesive layer of the coverlay film onto the conductor circuit, and performing thermal curing (C-stage formation) of the adhesive layer by heating and pressing. The thermal curing conditions for the adhesive layer are, for example, as follows. The curing temperature can be in the range of 80°C to 240°C, preferably in the range of 120°C to 220°C, more preferably in the range of 150°C to 200°C, even more preferably in the range of 170°C to 190°C, and the curing time can be in the range of 1 minute to 240 minutes, preferably in the range of 10 minutes to 180 minutes, more preferably in the range of 30 minutes to 120 minutes, and even more preferably in the range of 30 minutes to 90 minutes. The pressing pressure conditions for the heated press are preferably in the range of 0.5 MPa to 5 MPa, more preferably 1 MPa to 5 MPa, and even more preferably 2.5 MPa to 4.5 MPa.

[0093] This printed circuit board can have any lamination configuration that can be used as a printed circuit board. For example, it may be a printed circuit board composed of four layers: a resin substrate layer, a metal substrate layer, an adhesive layer, and another resin substrate layer. Alternatively, it may be a printed circuit board composed of five layers: a resin substrate layer, an adhesive layer, a metal substrate layer, an adhesive layer, and another resin substrate layer.

[0094] Furthermore, if necessary, the above-mentioned printed circuit boards may be stacked in a configuration of two or three or more layers.

[0095] 9. Semiconductor devices In this embodiment, the semiconductor device includes, for example, the printed circuit board described above.

[0096] Applications of this semiconductor device include electrical products (e.g., computers, mobile phones, digital cameras, and televisions) and vehicles (e.g., motorcycles, automobiles, trains, ships, and aircraft).

[0097] The semiconductor device in this embodiment can be manufactured, for example, by mounting components (semiconductor chips) on conductive locations on the printed circuit board described above. A "conductive location" is a "location on the printed circuit board that transmits electrical signals," and this location may be on the surface or embedded. The semiconductor chip is not particularly limited as long as it is an electrical circuit element made of semiconductor material.

[0098] The method for mounting semiconductor chips when manufacturing the aforementioned semiconductor device is not particularly limited as long as the semiconductor chip functions effectively, but specifically, wire bonding mounting methods, flip-chip mounting methods, bumpless build-up layer (BBUL) mounting methods, anisotropic conductive film (ACF) mounting methods, non-conductive film (NCF) mounting methods, etc., can be used. Here, "bumpless build-up layer (BBUL) mounting method" refers to "a mounting method in which a semiconductor chip is directly embedded in a recess of a printed circuit board and the semiconductor chip is connected to the wiring on the printed circuit board." [Examples]

[0099] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0100] [Preparation of resin composition, fabrication of adhesive sheets] First, the reactive polymer (A), dispersant (C), and filler (D) from the components shown in Table 1 were blended in the mass ratios shown in Table 1. Then, toluene was added to achieve a solid content concentration of 50% by mass, and the mixture was stirred for 30 minutes using a dissolver. After that, glass beads with a particle size of 1.00 to 1.40 mm (UNIBEAS® Super UB-2022S, manufactured by Unitika Glass Beads Co., Ltd.) were added, and bead mill dispersion was performed at 1000 rpm for 30 minutes using an EasyNano RMBII (manufactured by AIMEC Co., Ltd.). After dispersion, the glass beads were removed, epoxy compound (B) was added, and then toluene was added to achieve a solid content concentration of 50% by mass. The mixture was stirred and dissolved to prepare the resin compositions of Examples 1 to 12 and Comparative Examples 1 and 2. Comparative Examples 3 to 5 had the same resin composition as Examples 1 to 3, but were prepared by dissolver dispersion only, without bead mill dispersion.

[0101] Each of the resin compositions described above in Examples 1-10, 12, and Comparative Examples 1-5 was applied to the release surface of a 38 μm thick silicone-based release PET film (manufactured by Mitsui Chemicals Tohcello, SP-PET-O3-BU), and dried at 150°C for 5 minutes to produce a 30 μm thick adhesive layer (B-stage state). An adhesive sheet was prepared by laminating OPP coated paper (Sanei Chemicals Co., Ltd., WH52-P25CM) to cover the side of the adhesive layer opposite to the side in contact with the silicone-based release PET film, under the conditions of 70°C, 0.3 MPa, and 0.5 m / min using roll lamination. Here, the first release substrate is a laminate substrate (OPP coated paper), and the second release substrate is a coated substrate. (A 38μm thick silicone-based release PET film.)

[0102] In Example 11, an adhesive layer (Stage B) having a stress-relieving layer on one side was prepared by applying the resin composition of Example 11 to the stress-relieving layer of a silicone-based release PET film that had a stress-relieving layer pre-formed thereon, and then drying it in the same manner. Here, a silicone-based release PET film with a pre-applied stress relaxation layer was prepared by blending reactive polymer 1 in a ratio of 100 parts by mass and epoxy compound 1 in a ratio of 3 parts by mass, adding toluene, and coating the release surface of a silicone-based release PET film (manufactured by Mitsui Chemicals Tohcello, Inc., SP-PET-O3-BU), drying it at 150°C for 5 minutes, thereby creating a 5 μm thick stress relaxation layer on one side of the silicone-based release PET film. An adhesive sheet was prepared by laminating OPP coated paper (manufactured by San-ei Chemical Co., Ltd., WH52-P25CM) to cover the side of the adhesive layer opposite to the stress relaxation layer, under the conditions of 70°C, 0.3 MPa, and 0.5 m / min using roll lamination.

[0103] [Table 1]

[0104] The specific details of each component listed in Table 1 are as follows: Reactive polymer 1: Maleic acid-modified styrene-ethylene-butylene-styrene block copolymer (styrene content 30% by mass, weight-average molecular weight 95,000, acid value 10 mg KOH / g), Reactive polymer 2: Acid-modified polypropylene resin (weight-average molecular weight 35,000, glass transition temperature 20°C, acid value 12.5 mg KOH / g), Reactive polymer 3: Solvent-soluble polyimide resin (weight-average molecular weight 40,000-50,000, glass transition temperature 40°C), Reactive polymer 4: Polyester resin (number average molecular weight 16,000, glass transition temperature 15°C, acid value 17 mg KOH / g) Epoxy compound 1: TETRAD-X (glycidylamine type epoxy resin, manufactured by Mitsubishi Gas Chemical Company), Epoxy compound 2: HP-7200HHH (dicyclopentadiene type epoxy resin, manufactured by DIC Corporation) Dispersant 1: ANTI-TERRA-204 (wetting dispersant, manufactured by BYK), Dispersant 2: BYK-P-105 (wetting dispersant, manufactured by BYK Corporation) Dispersant 3: KBM-403 (epoxy silane coupling agent, manufactured by Shin-Etsu Chemical Co., Ltd.) Filler 1: Strontium titanate (paraelectric particles, no surface treatment, average primary particle size 0.3 μm), Filler 2: Calcium titanate (paraelectric particles, no surface treatment, average primary particle size 0.3 μm), Filler 3: Barium titanate (ferroelectric particles, no surface treatment, average primary particle size 0.5 μm), Filler 4: TITONE EX (high dielectric titanium oxide, paraelectric particles, surface treated, average primary particle size 1.0 μm, manufactured by Sakai Chemical Industry Co., Ltd.).

[0105] The adhesive sheets prepared as described above for Examples 1-12 and Comparative Examples 1-5 were evaluated using the following evaluation method. The results are shown in Table 2. [Relative permittivity and dielectric loss tangent] Each adhesive sheet from Examples 1-12 and Comparative Examples 1-5 was heated and pressed at 180°C, 4.0 MPa, for 60 minutes to allow complete curing. After complete curing, the first and second release substrates were peeled off to obtain samples for evaluating the relative permittivity and dielectric loss tangent (cured adhesive layers). The relative permittivity and dielectric loss tangent at each frequency at 23°C were measured using a millimeter-wave network analyzer (N5251A, Keysight Technologies) and a split-post dielectric resonator (QWED) or a split-cylinder resonator (EM Labs). A split-post dielectric resonator (QWED) was used at a frequency of 10 GHz, and a split-cylinder resonator (EM Labs) was used at frequencies of 28, 40, 60, and 80 GHz.

[0106] [Peel strength and solder heat resistance] Two adhesive sheets were prepared for each of Examples 1-12 and Comparative Examples 1-5. The first release substrate of each was peeled off, and the adhesive layers were roll-laminated together under the conditions of 140°C, 0.3 MPa, and 0.5 m / min to create peel-test adhesive sheets with an adhesive layer thickness of 60 μm (70 μm in Example 11). The second release substrate on one side of these peel-test adhesive sheets (the second release substrate on the stress-relaxation layer side in Example 11) was peeled off, and roll-laminated with 35 μm thick ultra-low roughness, unroughened electrolytic copper foil (CF-T9DA-SV-35, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd.) under the conditions of 140°C, 0.3 MPa, and 0.5 m / min. The remaining second release substrate from this laminate was peeled off and laid up on a double-sided copper-clad laminate (Nikaplex L-6705C2, manufactured by Nikkan Kogyo Co., Ltd.) with ANSI grade FR-4.1, an insulating layer thickness of 0.2 mm, and a copper foil thickness of 18 μm. The laminate was then heated and pressed at 180°C, 4.0 MPa for 60 minutes to bond and fully cure, thereby obtaining a sample for peel strength evaluation. The 35 μm thick copper foil side of the peel strength evaluation sample was subjected to a peel test at a 23°C atmosphere, with a tensile speed of 50 mm / min and peeling in the 90° direction, and the peel strength was measured. Solder heat resistance was evaluated by cutting a 25 mm x 25 mm test piece from the peel strength evaluation sample, drying it at 105°C for 1 hour, and then floating it in a solder bath at various temperatures for 30 seconds, measuring the temperature at which no appearance defects such as blistering occurred. The evaluation criteria for each item are as follows, and an evaluation of ○ or higher indicates sufficient performance. <Criteria for evaluating peel strength> ◎:1.0N / mm or more ○: 0.6 N / mm or more, less than 1.0 N / mm △: 0.1 N / mm or more, less than 0.6 N / mm ×: Less than 0.1 <Solder Heat Resistance Evaluation Criteria> ◎: Above 300℃ ○: 280℃ or higher, less than 300℃ △: Above 260℃, below 280℃ ×: Below 260℃

[0107] [Percentage change in thickness] After peeling off the first and second release substrates from each adhesive sheet in Examples 1-12 and Comparative Examples 1-5, the thickness was measured using a film tester thickness meter (Fujiwork HKT-1200) and defined as the "thickness before pressing." Similarly, each adhesive sheet in Examples 1-12 and Comparative Examples 1-2 was heated and pressed at 180°C, 4.0 MPa, for 60 minutes to allow complete curing. After peeling off the first and second release substrates, the thickness was measured again and defined as the "thickness after pressing." The rate of change in thickness was calculated using the following formula. Formula: Percentage change in thickness (%) = ((Thickness before pressing - Thickness after pressing) / Thickness before pressing) × 100

[0108] [Flexibility] Each adhesive sheet from Examples 1-12 and Comparative Examples 1-5 was heated and pressed at 180°C, 4.0 MPa, for 60 minutes to allow complete curing. After complete curing, the first and second release substrates were peeled off to obtain samples for evaluating bendability (cured adhesive layers). The obtained cured adhesive layers were cut into rectangles 50 mm long and 100 mm wide, folded 180 degrees, and a 0.5 kg weight was applied to the folded portion for 10 seconds. Afterwards, the samples were returned to a flat state and visually inspected for cracks or detachment. Example 11, which had a stress-relieving layer, was similarly evaluated after being folded so that the stress-relieving layer was on the outside. The evaluation criteria were as follows. <Evaluation criteria for flexibility> ○: No cracks or detachments. ×: Cracks or detachment present.

[0109] [Table 2]

[0110] [Discussion of Examples and Comparative Examples] Examples 1 to 12 provide a resin composition that stably exhibits a sufficiently high relative permittivity and a sufficiently low dielectric loss tangent in the frequency range of 10 GHz to 80 GHz. Therefore, by using this resin composition, an adhesive sheet that stably exhibits a sufficiently high relative permittivity and a sufficiently low dielectric loss tangent in a wide frequency range including the millimeter wave band can be provided. The resin compositions of Examples 1 to 9 not only stably exhibit the aforementioned sufficiently high relative permittivity and sufficiently low dielectric loss tangent, but also enable the production of adhesive sheets that exhibit extremely high flexibility, peel strength, and solder heat resistance. Therefore, by using these resin compositions, it is possible to provide highly reliable coverlay films, resin-coated metal foils, metal-clad laminates, printed circuit boards, and semiconductor devices that stably exhibit the aforementioned sufficiently high relative permittivity and sufficiently low dielectric loss tangent. This is thought to be due to the better balance of organic components and fillers in the resin composition. The resin composition of Example 10 was confirmed to have practical performance in terms of bendability, peel strength, and solder heat resistance. However, compared to the resin compositions of Examples 1 to 9, it contains a large amount of filler, resulting in a high dielectric constant of the resulting adhesive sheet, but the peel strength and solder heat resistance are relatively low. On the other hand, the resin composition of Example 11, while containing a large amount of filler, was confirmed to achieve both high dielectric constant and excellent bendability, peel strength, and solder heat resistance because the adhesive sheet has a stress relaxation layer. Comparing Examples 1-9 with Example 12, adhesive sheets made from any of the resin compositions consistently exhibited sufficiently high dielectric constants and sufficiently low dielectric loss tangents at 10 GHz to 80 GHz, and also showed excellent flexibility and peel strength. Furthermore, when one type of reactive polymer, consisting of polyimide resin, polyolefin resin, or styrene-based elastomer, was included, it was confirmed that the difference between the maximum and minimum values ​​of the dielectric loss tangent was even smaller, and the solder heat resistance was also higher.

[0111] Furthermore, according to Examples 1 to 12, compared to Comparative Examples 3 to 5, the change rate between the thickness of the adhesive layer before curing by heat pressing and the thickness after the adhesive layer has been completely cured can be kept to 36% or less. Therefore, the change in the impedance of the adhesive layer formed by this resin composition from the circuit design can be minimized, and the impedance as designed can be achieved. This is thought to be because, in Examples 1 to 12, the resin composition manufacturing process includes a bead milling step, which allows the filler to disperse uniformly without agglomerating, thus minimizing the change in thickness between the adhesive layer before curing by heat pressing and the adhesive layer after complete curing.

Claims

1. A resin composition containing a reactive polymer, an epoxy compound, and a filler, and dispersed by bead milling. The adhesive layer made of the resin composition has a relative permittivity of 5.0 or more at 10 GHz when fully cured, and a dielectric loss tangent of 0.01 or less at 10 GHz. The difference between the maximum and minimum values ​​of the relative permittivity selected from among several relative permittivity measurements taken in the range of 10 GHz to 80 GHz is 1.0 or less. The difference between the maximum and minimum values ​​of the dielectric loss tangent selected from among several dielectric loss tangents measured in the range of 10 GHz to 80 GHz is 0.004 or less. The rate of change in the thickness of the adhesive layer, which is determined based on the thickness of the adhesive layer made of the resin composition before curing by heat pressing and the thickness of the adhesive layer after it has been completely cured, is 36% or less. The reactive polymer is either a maleic acid-modified styrene-ethylene-butylene-styrene block copolymer or an acid-modified polypropylene resin. The acid-modified polypropylene resin satisfies the following conditions: weight-average molecular weight of 35,000, glass transition temperature of 20°C, and acid value of 12.5 mg KOH / g. The filler is strontium titanate or calcium titanate. A resin composition in which the average primary particle size of the filler is 0.1 μm or more and less than 1.0 μm.

2. The resin composition according to claim 1, wherein the content of the filler is 50 parts by mass or more per 100 parts by mass of the solid content of the resin composition.

3. The resin composition according to claim 1, wherein the content of the epoxy compound is 1 part by mass or more and 30 parts by mass or less per 100 parts by mass of the organic component contained in the resin composition, where the organic component is the component of the solid content of the resin composition excluding the filler.

4. A laminate comprising an adhesive layer formed from the resin composition described in claim 1, and a substrate in contact with at least one surface of the adhesive layer, A laminate in which the substrate is formed from one or more materials selected from the group consisting of resin, release resin, paper, release paper, and metal.

5. A coverlay film, adhesive sheet, resin-coated metal foil, or metal-clad laminate comprising the laminate described in claim 4.

6. A printed circuit board comprising the laminate described in claim 4, or the coverlay film, adhesive sheet, resin-coated metal foil, or metal-clad laminate described in claim 5.

7. A semiconductor device comprising a printed circuit board as described in claim 6.

8. A resin composition containing a reactive polymer, an epoxy compound, and a filler. 、 The adhesive layer made of the resin composition has a relative permittivity of 5.0 or more at 10 GHz when fully cured, and a dielectric loss tangent of 0.01 or less at 10 GHz. The difference between the maximum and minimum values ​​of the relative permittivity selected from among several relative permittivity measurements taken in the range of 10 GHz to 80 GHz is 1.0 or less. The difference between the maximum and minimum values ​​of the dielectric loss tangent selected from among several dielectric loss tangents measured in the range of 10 GHz to 80 GHz is 0.004 or less. A method for producing a resin composition in which the rate of change in the thickness of the adhesive layer, determined based on the thickness of the adhesive layer made of the resin composition before curing by heat pressing and the thickness after the adhesive layer has been completely cured, is 36% or less, The reactive polymer is either a maleic acid-modified styrene-ethylene-butylene-styrene block copolymer or an acid-modified polypropylene resin. The acid-modified polypropylene resin satisfies the following conditions: weight-average molecular weight of 35,000, glass transition temperature of 20°C, and acid value of 12.5 mg KOH / g. The filler is strontium titanate or calcium titanate. The average primary particle size of the filler is 0.1 μm or more and less than 1.0 μm. A mixing step of mixing the reactive polymer, the filler, and the epoxy compound, A method for producing a resin composition, comprising a kneading step of kneading the mixture obtained in the mixing step using a bead mill.

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